Two different types of granulocyte colony-stimulating factor produced by bovine lung tissue

Bovine lung tissue produces two different types of granulocyte colony-stimulating factor (CSF). The high molecular weight (MW) type (CSF-F) of 70,000 d by Sephadex G-100 gel filtration is only found in conditioned medium of homogenized tissue incubated in sealed glass bottles. The species of CSF exclusively stimulates CFU-C of mouse bone marrow, human bone marrow only hardly. The low MW type CSF (CSF-M) of approximately 29,000 d by gel filtration is found mainly in conditioned medium of slightly minced tissue incubated in Petri dishes. It stimulates both human and mouse CFU-C. Methods to prepare both types of CSF are described. By propagating a fibroblast cell line from bovine lung tissue it was found that fibroblasts are the source of the 70,000 d CSF. Indirect evidence suggests that macrophages produce the 29,000 d CSF species.